Recently, a touch panel has been applied to various electronic products, through which a user input is input by touching an image displayed on a display device with a finger or an input device such as a stylus.
Such touch panels may be largely divided into a resistive-film type touch panel and a capacitive touch panel. A touched position on the resistive-film type touch panel is detected as glass and an electrode are shorted by pressure applied by an input device. A touched position on the capacitive touch panel is detected by sensing a change in a capacitance between electrodes, caused when the touch pad is touched by a finger.
As the resistive-film type touch panel is repeatedly used, the performance of the touch panel may be lowered and the touch panel may be scratched. Thus, much attention has been paid to capacitive touch panels having high durability and long lifetime.
The capacitive touch panel is defined as having an effective region into which a touch command may be input and an ineffective region outside the effective region. In the effective region, an electrode pattern is formed of a transparent conductive material to transmit light from a display device.
Conventionally, the electrode pattern is formed of an indium-tin oxide (ITO). The ITO is limited in terms of a high sheet resistance, high manufacturing costs, and imbalance between the supply and demand of indium in a raw material market. Furthermore, the ITO is not available for a flexible display apparatus which is a recent trend.
Recently, research has been conducted on a transparent electrode material such as silver nanowire which may replace the ITO.
FIG. 1 is a diagram illustrating a transparent electrode formed of conventional silver nanowires.
Referring to FIG. 1, conventionally, an aspect ratio of silver nanowires 200 is limited due to material and manufacturing process constraints, and the silver nanowires 200 are manufactured each having a small diameter of about 100 nm to achieve high transmissivity. As a result, the silver nanowires 200 having a relatively short length of 5 um to 10 um are applied to a transparent electrode.
The silver nanowires 200 are required to have high conductivity in order to be applied to a transparent electrode. However, the silver nanowires 200 have a short length and thus have low conductivity due to many disconnections between the silver nanowires 200.
Furthermore, as illustrated in FIG. 2, an organic film 210 exists on a surface of each of the silver nanowires 200 and thus a resistance of contact regions between the silver nanowires 200 increases. In addition, an additional process should be performed to electrically connect the silver nanowires 210, thereby increasing manufacturing costs.